Smith College works on sinkhole near Paradise Pond

NORTHAMPTON — Work to repair a sinkhole that swallowed up a paved path on the hill overlooking Smith College’s Paradise Pond is underway.

The sinkhole opened up in mid-May and is 15 feet in diameter and 12 feet deep, according to Smith College spokeswoman Stacey Schmeidel.

Located about halfway down the hill between the admissions office and the pond, the hole bisects a path — now blocked off by sawhorses and fencing — that leads to a trail along the Mill River bank.

Schmeidel said that since grounds workers noticed the sinkhole in May, the college has been working with a civil engineering firm to determine the best way to fix it to prevent future washouts.

This week, work is underway to replace the old stormwater pipe that failed, causing the washout. She said the project is expected to be complete in seven to 10 days.

“Obviously, if it rains every day, it’s going to take longer,” Schmeidel said. The National Weather Service is forecasting storms bringing heavy rain through Tuesday, with total rainfall possibly nearing three inches.

A number of deluges occurring since May exacerbated the sinkhole, she said. The washout occurred after the failure of an underground clay tile pipe — estimated to be between 40 and 100 years old — that carried stormwater runoff into Paradise Pond. “Nature happens, something shifted,” Schmeidel said, until water could no longer flow through the pipe, instead traveling down the hillside and causing the washout. The new pipe will again collect runoff and channel it into the pond.

The Conservation Commission gave the college emergency permission to complete the work at its June 26 meeting, said Sarah LaValley, the city’s conservation, preservation and land use planner. She said the college’s plans included steps to prevent disturbing Paradise Pond, in accordance with wetlands regulations. It also addressed the Department of Public Works’ concerns that a buried sewer main at the site not be affected by the work, she said.

The work did require Smith College Facilities Management to temporarily lower the level of the pond several feet by releasing more water from the dam downstream, Schmeidel said. Depending on rainfall, it could take several days to refill after the work is complete, according to a statement about the project on the Smith College website.